#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#define I inline
using namespace std;

const int N = 220;
char s[N][N*11];
int n,m,k;

int main()
{
	cin>>n>>m>>k;
	for(int i=1;i<=n;++i) scanf("%s",(s[i]+1));
	int difx=0,dify=0;
	for(int i=1;i<=k;++i) {
		for(int j=1;j<=n;++j) {
			for(int p=1;p<=m;++p) {
				if(s[j][(p-1)*k+i]!=s[1][i]) {	
					if((difx||dify)&&(difx!=j||dify!=p)) {
						cout<<1<<' '<<1<<endl;
						return 0;
					}
					difx=j;
					dify=p;
				}
			}
		}
	}
	cout<<difx<<' '<<dify<<endl;
}